Does computer navigation in total knee arthroplasty improve patient outcome at midterm follow-up?

Computer navigation assistance in total knee arthroplasty (TKA) results in consistently accurate alignment of prostheses. We aimed to compare the outcome of computer-navigated and conventional TKA and to analyse the radiologically malaligned knees. We analysed 637 primary TKA, carried out by a single surgeon, over five consecutive years and divided them into two cohorts: group 1 = STA (standard instrumentation) and group 2  = CAS (computer-assisted surgery). There was no significant difference between the average Oxford Knee Scores (OKS) of the two groups at any time from one to five years. However, the malaligned TKA at three years had a worse OKS. At medium term there is no difference in clinical outcome measures that can be attributed to the surgeon having used computer-assisted navigation for TKA. But group 1, having a higher proportion of malaligned TKA, might show worsening of OKS at long term.